[PATCH v1 2/2] device property: Fix fwnode_name_eq() for empty node names

[Alejandro Colomar]

str_has_prefix() returns the prefix length on match and 0 on mismatch,
so the mistmatch case can't be told from "empty prefix matched an empty
string".

For instance: the OF root node's name as returned by
fwnode_get_name() is "" and will return 0 for any name matched against
it and since len is 0 too, fwnode_name_eq() will return true.

Let's use strprefix() instead, which also makes this function simpler.

Fixes: a9c8c738066b7 ("device property: Add fwnode_name_eq()")
Reported-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
Cc: Andreas Schwab <schwab@xxxxxxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Andy Shevchenko <andy@xxxxxxxxxx>
Cc: Bartosz Golaszewski <brgl@xxxxxxxxxx>
Cc: Daniel Scally <djrscally@xxxxxxxxx>
Cc: Danilo Krummrich <dakr@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Cc: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Johan Hovold <johan@xxxxxxxxxx>
Cc: Kees Cook <kees@xxxxxxxxxx>
Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Cc: Len Brown <lenb@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Walleij <linusw@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
Cc: Saravana Kannan <saravanak@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Tom Zanussi <zanussi@xxxxxxxxxx
Cc: linux-acpi@xxxxxxxxxxxxxxx
Cc: driver-core@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-hardening@xxxxxxxxxxxxxxx
Cc: devicetree@xxxxxxxxxxxxxxx
Cc: linux-gpio@xxxxxxxxxxxxxxx
Signed-off-by: Alejandro Colomar <alx@xxxxxxxxxx>
---
 drivers/base/property.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 51109794d727..7728116e2968 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -692,15 +692,12 @@ const char *fwnode_get_name_prefix(const struct fwnode_handle *fwnode)
 bool fwnode_name_eq(const struct fwnode_handle *fwnode, const char *name)
 {
 	const char *node_name;
-	ptrdiff_t len;
 
 	node_name = fwnode_get_name(fwnode);
 	if (!node_name)
 		return false;
 
-	len = strchrnul(node_name, '@') - node_name;
-
-	return str_has_prefix(node_name, name) == len;
+	return strprefix(node_name, name) == strchrnul(node_name, '@');
 }
 EXPORT_SYMBOL_GPL(fwnode_name_eq);
 
-- 
2.55.0

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